SECRETION OF BILE. 629 



MAX. Ox. 



Water ....... 90-44 92-84 



Biliary matter ...... 8'00 5'00 



.Mucus ....... -30 -23 



Alkali (in combination with fatty acids) . . '41 



Chloride of sodium, and extractive . . . '74 1'50 



Phosphates and sulphates of soda and lime . . -11 '43 



10OOO 100-00 



In the Biliary matter, we are to distinguish at least three distinct substances ; Cholesterine, 

 Bilic acid, and Colouring matter. In healthy bile, the proportion of Cholesterine appears to 

 be very small ; but in many disordered states of the secretion, and especially in disease of 

 the Gall-bladder, this substance is present in much larger amount; and it usually forms the 

 principal, if not the sole, ingredient in biliary concretions. It is a white crystallizable fatty 

 matter, somewhat resembling Spermaceti ; free from taste and odour ; not. soluble in water, 

 but dissolving freely in alcohol, from which it is deposited on cooling in pearly scales. It 

 is almost entirely composed of Carbon and Hydrogen ; its constitution being 36 Carbon, 32 

 Hydrogen, 1 Oxygen. It may be obtained by a chemical process of no great complexity, 

 from the Serum of the Blood ; and it is not unfrequently deposited as a result of diseased ac- 

 tion in other parts of the body, especially in the fluids of local Dropsies, as hydrocele, ovarian 

 dropsy. &c. 



b. The principal constituent of Bile is a compound of soda with a peculiar organic body; 

 which is now generally regarded in the light of a fatty acid, and named Bilic acid. Accord- 

 ing to Plainer, this bilic acid and the bibilate of soda may be obtained in a pure crystalline 

 state from fresh bile; a yellowish-brown syrup being left, which seems principally to consist 

 of colouring matter diffused through the water. No analysis has yet been made of bilic acid 

 thus purified; that of Dr. Kemp, made upon an impure bilic acid, gives as its ultimate com- 

 position 48 Carbon, 42 Hydrogen, 13 Oxygen, and 1 Nitrogen. This is the substance described 

 by different Chemists (doubtless under various modifications, according to the process used 

 to obtain it), as Choleic acid, Bilin, Picromel, &c. It is very readily altered by reagents, espe- 

 cially by acids; and a great variety of products may be formed by its decomposition. Some 

 of these appear to present themselves in the living body, as results of disordered conditions 

 of the secreting process. 



c. The colouring matter of the bile is now termed Biliverdin. That of the Ox contains no 

 azote; and appears to be identical with the Chlorophyl of plants. That of Man, however, 

 contains about 7 per cent, of Azote, with 68 parts of Carbon, 7^ of Hydrogen, and 17| of 

 Oxygen; and it cannot be derived so directly from the food. When exposed to the air, it 

 becomes of a deep green absorbing oxygen ; and the same change is produced by nitric acid, 

 the liquor soon passing, however, to a red hue. This frequently takes place within the 

 body, in cases of Jaundice ; but more especially in the urine. Though the colouring matter 

 is usually present but in small quantity during health, it sometimes accumulates in disease, 

 so as to produce solid masses, which include little else. 



834. The amount of the secretion of Bile appears to bear some proportion 

 to that of the Food digested. That its formation is continually going on to a 

 certain degree appears unquestionable ; but that its quantity is greatly increased 

 during the' solution of food in the stomach, appears also to be well established. 

 In those animals which are most constantly ingesting food, we find no Gall- 

 bladder : for in them, the Bile may be poured into the Intestine as fast as it is 

 formed. In those which only take food occasionally, on the other hand, and 

 which are provided with a Gall-bladder, the Bile, when not required in the 

 Intestine, flows back into that reservoir. This reflex would appear due to the 

 valve-like termination of the Ductus Choledochus in the walls of the Intestine; 

 by which a certain resistance is offered to the entrance of the fluid, unless it 

 be propelled by some decided force. The flow of Bile into the Intestinal tube, 

 when its action is needed there, is commonly imputed to the pressure of the 

 distended Duodenum against the Gall-bladder; it may be doubted, however, 

 whether the contractile power of the Duct itself does not afford important aid 

 in the process; and it is easy to understand, from the known influence of the 

 Sympathetic system of nerves upon it ( 825, /), that peristaltic movements 

 may be thus excited at the time when they are needed. It is an interesting 

 fact, proving how completely the passage of Bile into the Intestine is depend- 



53* 



